一般而言，某种生物的体温每下降 10 摄氏度，其代谢活动会减少约 50% 。然而，美国研究人员 2 月 17 日公布的最新发现表明，尽管阿拉斯加黑熊冬眠时体温只下降 5 到 6 摄氏度，其代谢活动却急剧下降，只有正常水平的 25% 。 阿拉斯加大学费尔班克斯分校及斯坦福大学研究人员监控了部分黑熊 5 个月的冬眠时间，他们观察到，这些熊的体温缓慢地以 2 到 7 天为周期在 30 至 36 摄氏度之间波动。这种现象从未在较小的冬眠动物中发现，而且研究人员此前也根本不知道在哺乳动物中存在这种情况。 通过测量黑熊在模拟巢穴中冬眠时的氧气消耗量，研究人员发现，这些黑熊的代谢活动比夏天时的水平低 75% ，其心率也会从每分钟 55 跳减缓至 14 跳。此外，研究人员还发现，这些黑熊冬眠结束之初，其代谢活动仍然只有正常水平的一半， 2 到 3 周后才完全恢复正常水平。 这项研究成果发表在新一期美国《科学》杂志上。 研究人员表示，黑熊冬眠醒来时，其肌肉、骨质等都完好，功能都没有丧失，如果能够发现黑熊这一本领的遗传学奥秘以及降低代谢需要的机制，就有可能开发出新的治疗方法和药物，用于预防骨质疏松、废用性肌萎缩，甚至可将受伤者置放到某种活动力暂停或降低的状态，直到他们能接受先进医疗护理，即把抢救治疗的黄金小时延长为黄金日或黄金周。（来源：新华网任海军） Science 18 February 2011: Vol. 331 no. 6019 pp. 906-909 Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature ivind Tien 1 , * , John Blake 1 , Dale M. Edgar 2 , † , Dennis A. Grahn 3 , H. Craig Heller 3 , and Brian M. Barnes 1 , * Author Affiliations 1 Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA. 2 Department of Psychiatry and Behavioral Sciences, School of Medicine, Stanford University, CA 94305, USA. 3 Department of Biological Sciences, Stanford University, CA 94305, USA. Author Notes * To whom correspondence should be addressed. E-mail: otoien@alaska.edu (O.T.); bmbarnes@alaska.edu (B.M.B.) † Present address: Lilly Research Centre, Eli Lilly, Windlesham, Surrey, GU20 6PH, UK. Abstract Black bears hibernate for 5 to 7 months a year and, during this time, do not eat, drink, urinate, or defecate. We measured metabolic rate and body temperature in hibernating black bears and found that they suppress metabolism to 25% of basal rates while regulating body temperature from 30° to 36°C, in multiday cycles. Heart rates were reduced from 55 to as few as 9 beats per minute, with profound sinus arrhythmia. After returning to normal body temperature and emerging from dens, bears maintained a reduced metabolic rate for up to 3 weeks. The pronounced reduction and delayed recovery of metabolic rate in hibernating bears suggest that the majority of metabolic suppression during hibernation is independent of lowered body temperature.
标签: 黑熊
